Evaporation rate for keggle

Just wondering what some of you other guys with keggles are getting for boil off/evaporation rates. I just wrapped up a batch this afternoon and it looks like I boiled off 1.96 gallons during a 60 minute boil... And, well, that seems abnormally high... I know this is very much a YMMV type of question, but doesn't that seem a tad high?

10 gallons?

5 gallons.

I get roughly 1.3 gallon/hour with a keggle depending on RH and boil vigor. I just switched to a SQ-14 burner and I think I'm getting a tad more than that now. Nearly 2 gallons sounds a little high, but it's possible, especially with a very vigorous boil and low humidity.

mine is low, I am going electric soon so that might have some impact. I use a big when I boil and I think that increases boil off rate....but i don't know for sure

Switching to a keggle increased my boil off rate to 1.9 gal/hr (from about 1.6 gal/hr in a 8 gal kettle)

Hmmmm, so it sounds like it might just be that high. Thanks for the input guys, I was skeptical as hell when I did the math earlier, but I guess it was right.

Looks like I will have to brew again and double check it all!

badbrew said:

10 gallons?

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doesn't matter

I'm at 1.9 GPH too. The reason Passedpawn said 10 gallons doesn't matter is that the boil off rate is static. It will be 1.9 GPH no matter what volume.
Also remember it will shrink 4% from boil Vs. cool.

passedpawn said:

doesn't matter

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It does matter, if you look at it from a boil-off percentage basis.

5 gallon batch
1.9gal/6.9gal*100 = 27.5%

10 gallon batch
1.9gal/11.9gal*100 = 15.9%

The brewing calculators I use, calculate water volumes based on boil-off percentage/hr, so volume is necessary for me at least.

mthompson said:

It does matter, if you look at it from a boil-off percentage basis.

5 gallon batch
1.9gal/6.9gal*100 = 27.5%

10 gallon batch
1.9gal/11.9gal*100 = 15.9%

The brewing calculators I use, calculate water volumes based on boil-off percentage/hr, so volume is necessary for me at least.

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Whoever first choose to release programs with percentage based evaporation should be flogged. Glad beersmith is using gallons/hr now. To the OP, 1.38 gal/hr. I found it constant between two pots, I just need to make sure I have my propane regulator set to the same position everytime.

I typically burn off 1.5 gals per 60 min boil. A little more when its cold.

Humidity is a big factor for me. In the summer, I boil off about 1-1.25 gallons per hour. In the winter, it's easily 2 gallons per hour with the same system! We have a very dry winter climate- even the snow is dry to the touch.

mthompson said:

It does matter, if you look at it from a boil-off percentage basis.

5 gallon batch
1.9gal/6.9gal*100 = 27.5%

10 gallon batch
1.9gal/11.9gal*100 = 15.9%

The brewing calculators I use, calculate water volumes based on boil-off percentage/hr, so volume is necessary for me at least.

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Don't use calculators that determine boil-off based on a percentage of the total volume. They are wrong.

passedpawn said:

Don't use calculators that determine boil-off based on a percentage of the total volume. They are wrong.

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Right. In the same pot, you'll have the same amount of boiloff (NOT a percentage) no matter what the volume.

If you have a 1 gallon per hour boil off rate, you'll boil off 1 gallon whether you start with 3 gallons or 15 gallons.

When I make a 10 gallon batch, I start with 12 gallons. When I make a 5 gallon batch, I start with 7 gallons. In the winter, at my house, I boil off two gallons per hour. In the summer, I boil off 1.25 gallons per hour.

I'm at around 2.50 gph in a keggle. Not sure why but it's that high, yes. 13.75 to the kettle - 11 gallons to the fermenters - 0.25 gallon left behind (that's a bit generous) = 2.50 GPH.

MC

2.5 g/h??? What are you using as a burner, a jet engine? Good grief Charlie Brown!

It's also a big function of how much heat you're putting into the water. I use a 5500w electric element in my keggle and I boil of almost exactly 1.25 gph on 60% power, which seems to be a good balance for me and my setup. When I have accidentally oversparged, though, I have cranked the power up to 80% and get about 1.75 gph. The boiloff rate will scale approximately linearly with your power input.

For ref. when I used to have a sq-12 and keggle setup I would routinely boil off 2-2.5 gph. I always had a problem getting a nice rolling boil. It was either too violent or a strong simmer. The air shutter on my burner was too touchy.

I'm on the low end: 1GPH

I use the Blickman Floor Burners and get a really good rolling boil, I could however crank it up further and adjust dampers and boil off more, but I don't see a benefit unless like you said I needed to boil off more, but I've always just boiled off longer if I needed to. I try not to ever go longer than 90 mins though.

Snafu said:

2.5 g/h??? What are you using as a burner, a jet engine? Good grief Charlie Brown!

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Yep 2.5 GPH, or right around. I use a cajun cooker, it boils fast for 60 minutes. It's possible that my pre-heating (I get to 210F while I'm finishing the sparge) may be part of that.

MC

Snafu said:

2.5 g/h??? What are you using as a burner, a jet engine? Good grief Charlie Brown!

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He's really, really afraid of getting any DMS flavors in his beer.

And he owns a propane business.

LandoLincoln said:

He's really, really afraid of getting any DMS flavors in his beer.

And he owns a propane business.

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LOL Unless of course I can't measure anything for cr*p.

MC